Air purge systems have traditionally been employed to protect particular surfaces or areas from various hazards present in the surrounding environment. For example, the air in a factory may include airborne droplets of oil, water or other fluids, dirt, dust, manufacturing scraps, metallic particles, and/or a variety of other particulates. In such an environment, an air purge system may be useful, e.g., to prevent particulates from interfering with the function of an imaging system. Such particulates may interfere with optical imaging systems, infrared or other thermal imaging systems, laser systems, x-ray systems, ultrasonic systems, and/or the like.
To accomplish this objective, traditional air purge systems may employ a tube, shroud, or other conduit that blows clean dry air near the particular surface or area. For instance, an imaging system often requires a clear view of the object or area of interest, and an associated air purge system may include one or more tubes that continually blows clean, dry air past a viewing window or lens of the imaging system. Such blowing may push contaminants in the ambient air away from the viewing window or lens and thereby prevent dirt or other particulates from contacting or adhering to the viewing window of the imaging system.
In one application, a housing or tube may extend outwardly from the lens or viewing window and enable clean dry air to be introduced such that ambient air is pushed away from the lens. However, housings and tubes of this type may limit the field of view, cause vignetting in wide field of view applications, or provide insufficient isolation or protection of the imaging system from the ambient air. For example, some air purge systems employing tubes may generate turbulent air flow in the vicinity of the imaging system viewing window or lens and fail to provide consistent protection from contaminants over the entire area or surface for which protection is sought.
The increasing use of imaging applications in a variety of settings has resulted in increased demand for wider field of view imaging products, such as thermal imaging products. Infrared and other thermal imaging systems typically use a wide field of view, resulting in relatively large optical components, lenses, or protective viewing windows. In addition, combined optical/thermal imaging systems may include an integrated visible light camera as well as a thermal imager to provide a fused visible/thermal image, which increases the size of the optical components even further and correspondingly increases the size of the area or surface for which protection from contaminants is sought. There is thus a need for improved air purge systems capable of protecting larger areas and surfaces from contamination in a consistent and effective manner.